Dental erosion -- the loss of the protective enamel on teeth -- is reportedly on the increase in the United States. The condition occurs when enamel is worn away by acids in the mouth, leaving teeth sensitive, cracked and discolored.

"Erosion is a chemical process of tooth destruction, not to be confused with abrasion, which is a mechanical process of tooth destruction," said Dr. Melvin Pierson, a spokesman for the Academy of General Dentistry and a dentist in private practice in Sicklerville, N.J.

One study, for instance, found dental erosion in about 30 percent of a group of 900 middle school students across the country. Pierson said those results, published in 2008 in the Dental Tribune, confirmed the suspicions many dentists had harbored. In a survey of dentists taken before the study, nearly half said they thought tooth erosion was on the rise.

Why is this happening? Experts blame what people are drinking and how theyre drinking it, for the most part.

Soft drinks, sports drinks, fruit juices and teas all contain high amounts of acid, said Dr. Edmond R. Hewlett, consumer adviser for the American Dental Association and an associate professor of restorative dentistry at the University of California, Los Angeles, School of Dentistry.

"When we're talking about erosion, it's clearly the acid content that's causing it," Hewlett said. "In soft drinks, especially in cola soft drinks, one of the main flavoring agents is phosphoric acid. That's the acid we use in dentistry to roughen tooth enamel before applying a bonding agent. We use it like sandpaper."

The sugar in most of those drinks also plays a role. When bacterial plaque on the teeth absorbs sugar from drinks and foods, it excretes an acid that eats away at tooth enamel.

"If you are eating sugary foods, the acidity of the plaque on your teeth increases precipitously," Hewlett said.

People often make the situation worse by savoring juices and soft drinks. Holding them in the mouth to enjoy the flavor or the fizzing increases exposure to the acids and sugars in the drinks. "You cause more damage when you drink a large amount and hold it in your mouth to savor the flavor," Pierson said.

Other things contribute to dental erosion, too. Medications such as aspirin can cause erosion, as can conditions such as acid reflux disease or eating disorders associated with chronic vomiting, which expose the teeth to gastric acid.

Pierson believes that dental erosion also is increasing because people are not getting enough fluoride. Many people are eschewing fluoridated public water sources in favor of bottled water, which might not contain fluoride. And they're also substituting soft drinks and juices for water.

"Fluoride helps strengthen the enamel. Erosion is an attack on the enamel," Hewlett said. "You have something that's going to protect it and strengthen it when it's under attack." He recommends that people who aren't drinking public water use a fluoridated toothpaste and mouth rinse.

Another way to help stop erosion is to hold off on brushing your teeth for about a half-hour after drinking a soda or a glass of juice, Hewlett said. If you brush right after, you're adding insult to injury by scrubbing at enamel already softened by the acid attack

"You've removed a microscopic layer of enamel that could have been replenished by the minerals in your saliva," he explained.

Saliva, it turns out, helps protect teeth from people's bad behavior by working to return the pH balance in the mouth to normal and restore minerals leached away by food acids, Hewlett said.

"There's this constant balance in the mouth, and saliva is there as our first line of defense," he said. "If someone has a good saliva flow, it can help repair some of the damage."

People who are worried about tooth erosion should talk about it with their dentist during one of the two visits a year they should be making to the dentist's office, Pierson said.

"That's where you get education from your dentist one-on-one," he said. "They examine your mouth and can ask specific questions based on what they find to address your specific problems."